1. Field of the Invention
The present invention relates to an electronic apparatus including a disk apparatus which makes access to a disk such as a hard disk and a magneto optical disk by rotating the disk while freely stopping the disk and a disk apparatus which makes access to a disk in which information is written and read by rotating the disk while freely stopping the disk.
2. Description of the Related Art
Recently, portable devices such as a so-called notebook type personal computer (notebook PC) into which a hard disk apparatus is incorporated become widespread. The hard disk apparatus makes access to the disc-shape hard disk in which the information is written and read during the rotation of the disk by rotating the hard disk while freely stopping the hard disk.
FIG. 11 is a block diagram showing a conventional hard disk apparatus incorporated into the notebook PC.
A hard disk apparatus 100 of FIG. 11 includes plural disc-shape hard disks 101 in which the information is written and read during rotation of the hard disk. The hard disk apparatus 100 includes plural heads which make access to the disc-shape hard disk 101 while coming close to the surfaces of the hard disks 101. The hard disk apparatus 100 includes a head circuit 102 having plural preamplifier units corresponding to the plural heads. In the head circuit 102, the preamplifier unit amplifies a signal indicating the information from the hard disk 101 which is read by the head arranged corresponding to the hard disk 101, and a signal for writing the information in the hard disk 101 is supplied to the head while the preamplifier unit is used as a buffer.
The hard disk apparatus 100 also includes a head selection circuit 103, a recording and reproducing circuit 104, a serial-parallel conversion circuit 105, a disk control circuit 106, an interface control circuit 107, and a buffer memory 108.
The head selection circuit 103 outputs the signal from the selected head to the recording and reproducing circuit 104, and the head selection circuit 103 outputs the signal from the recording and reproducing circuit 104 to the selected head.
The recording and reproducing circuit 104 outputs a reproducing serial signal from the head selection circuit 103 to the serial-parallel conversion circuit 105, and also outputs a recording serial signal for recording to the hard disk 101 transmitted from the serial-parallel conversion circuit 105 to the head selection circuit 103.
The serial-parallel conversion circuit 105 converts a parallel signal from the disk control circuit 106 into the serial signal to output the converted signal to the recording and reproducing circuit 104, and the serial-parallel conversion circuit 105 converts the serial signal from the recording and reproducing circuit 104 into the parallel signal.
The disk control circuit 106 inputs the parallel signal from the serial-parallel conversion circuit 105, constructs the inputted parallel signal in a sector unit including the predetermined number of bytes to perform error correction and the like, and outputs the signal through the interface control circuit 107 to a CPU 200 included in the notebook PC into which the hard disk apparatus 100 is incorporated. The disk control circuit 106 performs a coding process to the parallel signal inputted from the CPU 200 through the interface control circuit 107, and outputs the signal to the serial-parallel conversion circuit 105.
The interface control circuit 107 controls the disk control circuit 106 and the buffer memory 108 based on a command from the CPU 200, and transfers the parallel signal from the disk control circuit 106 or the buffer memory 108 to the CPU 200.
The buffer memory 108 is a volatile memory in which contents are deleted when the power is turned off. The parallel signal inputted from the CPU 200 through the interface control circuit 107 is tentatively stored in the buffer memory 108, and also the parallel signal inputted from the serial-parallel conversion circuit 105 through the disk control circuit 106 is tentatively stored in the buffer memory 108.
In the portable device into which the hard disk apparatus is incorporated, there is a demand for shortening a start-up time necessary to become a user working environment in which the user can work after the power is turned on. For this end, it is necessary to rapidly start up an operating system (hereinafter abbreviated to OS) which controls the portable device. OS is stored in the hard disk apparatus and thus, it is important to shorten the start-up time of the hard disk apparatus to rapidly start up the portable device. However, in the hard disk apparatus, a predetermined time is required until the hard disk is stably rotated after the power is turned on. There is a problem that the information stored in the hard disk can be read or the information can be written into the disk only after the predetermined time elapses.
Japanese Patent Application Laid-Open No. 2003-216435 discloses a technique wherein, in a computer system including a hard disk apparatus and a main memory, OS boot information is stored in a nonvolatile memory provided in the hard disk apparatus, the boot information is read from the nonvolatile memory and transferred to a main memory before a motor of the hard disk apparatus reaches a steady speed, and thereby the start-up time is shortened in the hard disk apparatus after the power is turned on.
Japanese Patent Application Laid-Open No. 10-254770 discloses a technique wherein, in an information processing device including a hard disk apparatus, a nonvolatile memory, a cache memory and a signal processing unit, pieces of information on a storage position, an amount of data, data reading order of an OS read from the hard disk apparatus are stored in the nonvolatile memory, the OS is read from the hard disk apparatus and stored in the cache memory based on the pieces of information stored in the nonvolatile memory when the power is turned on to confirm the normal operation of the hard disk apparatus, and the signal processing unit performs the process with OS stored in the cache memory when a read command is issued from the signal processing unit at the time an initializing operation is finished in the whole of the information processing device. According to the technique disclosed in Japanese Patent Application Laid-Open No. 10-254770, OS is read from the cache memory to perform the process at the time the initializing operation is finished, so that the start-up time can be shortened in the information processing device compared with the case where OS is read from the hard disk apparatus at the time the initializing operation is finished.
Japanese Patent Application Laid-Open No. 8-137622 discloses a technique wherein a nonvolatile memory in which a particular address range of an address space of a hard disk apparatus is allocated is provided in the hard disk apparatus, the access is made to the nonvolatile memory when a disk address indicated by a disk access command from a host apparatus is located within the particular address range, and thereby the speed-up in reading the data is achieved in the particular address range.
Japanese Patent Application Laid-Open No. 7-44325 discloses a technique wherein a nonvolatile memory is provided in a hard disk apparatus, information necessary to load an OS in the hard disk apparatus is stored in the nonvolatile memory, and the information is read from the nonvolatile memory to shorten the start-up time of the hard disk apparatus when the hard disk apparatus is started up.
Japanese Patent Application Laid-Open No. 2004-30184 discloses a technique wherein, in booting a personal computer with an OS, the OS previously stored in the hard disk apparatus is re-constructed into a data array that can be read at high speed and stored in the hard disk apparatus, and the boot process is performed at high speed with the OS in which the data array is reconstructed, when the personal computer is booted.
Because a portable device into which a hard disk apparatus is incorporated is frequently driven by a battery, low power consumption is a large problem in the hard disk apparatus. In order to lengthen a battery life as long as possible, frequently the power is turned off during nonuse of the portable device while the power is turned on in use. Therefore, start-up time shortening is also the important problem in the hard disk apparatus. Sometimes OS stored in the hard disk apparatus is updated (version-up) while the power is turned on. However, in the techniques disclosed in Japanese Patent Application Laid-Open No. 2003-216435, Japanese Patent Application Laid-Open No. 8-137622, and Japanese Patent Application Laid-Open No. 7-44325, there is no description concerning the process performed in the nonvolatile memory when the power is turned on again after the power is turned off. Accordingly, even if the OS is updated while the power is turned on, there is a risk of booting the device with pre-update OS when the power is turned on again after the power is turned off.
In the technique disclosed in Japanese Patent Application Laid-Open No. 10-254770, after the power is turned on, it is necessary to wait to read the OS from the hard disk apparatus until the hard disk is stably rotated at the predetermined number of revolutions. In the technique disclosed in Japanese Patent Application Laid-Open No. 2004-30184, after the power is turned on, it is necessary to wait to read the data of the OS in which the data array is reconstructed from the hard disk apparatus until the hard disk is stably rotated at the predetermined number of revolutions. Accordingly, it is difficult to shorten the start-up time of the hard disk apparatus.
The hard disk apparatus includes a motor which stably rotates the hard disk at the predetermined number of revolutions while the information stored in the hard disk is read or the information is written in the hard disk. The motor requires relatively large power consumption, which makes the hard disk apparatus require large power consumption as well.
Conventionally, information to be written in the hard disk which is transmitted from the outside is tentatively stored in a buffer memory included in the hard disk apparatus, the motor is driven to rotate the hard disk at the time the write information reaches a predetermined capacity so as to transfer the information to be written in the hard disk to the hard disk. Therefore, low power consumption can be achieved in the hard disk apparatus as compared with the case where the write information is written in the hard disk by driving the motor in each time the write information is transmitted from the outside.
Although the conventional buffer memory is a volatile memory in which contents is deleted when the power is turned off, the power is turned off after the information stored in the buffer memory is transferred to the hard disk, when a command for turning off the power is received. However, sometimes there is a case where the power is turned off because a power cord is mistakenly removed or battery voltage is decreased. In this case, the electric power necessary for the power turn-off process cannot be supplied to the hard disk apparatus, so that the information cannot be transferred to the hard disk or the transfer is interrupted. In such cases, the power is turned on again, the hard disk information is read to confirm contents after the hard disk is stably rotated at the predetermined number of revolutions, and the necessary information is written in the buffer memory from the outside again. Accordingly, it is difficult to achieve start-up time shortening and low power consumption.
In other conventional disk apparatus such as a magneto optical disk apparatus including a magneto optical disk, there is also a problem that start-up time shortening and low power consumption is hardly achieved.